Electrophotographic printing device of modular construction

ABSTRACT

An electrophotographic printing device of modular construction with a support device, including a transport device, upon which a substrate may be transported between a start position and a target position and one or several electrophotographic units arranged on the support device, between the start and target position, having a developer unit, a photoconductor and an illumination unit for the photoconductor. The support device includes two or more housing positions arranged one behind the other in the transport direction of the transport device, provided with unitary mechanical interfaces. The electrophotographic units include unitary fixing pieces which are complementary in form to the interfaces. Such a printing device may be flexibly laid out due to the technical assembly thereof and may be individually set-up easily for specific printing jobs.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a modularly constructed electrophotographicprinting device with a support device, having a transporting device onwhich a substrate to be imprinted can be conveyed between a start and afinish position, wherein several electrophotographic units can bearranged on the support device between the start and finish positions,which are embodied as a photo conductor, a developer unit, an exposureunit and the like.

2. Discussion of Related Art

A printing device of this type is known from European Patent ReferenceEP-B-0 932 851. With this known printing device, the units required forthe printing process are arranged behind each other in a definitesequence, beginning at the start position in the direction toward thefinish position. The units are designed for a particular printingprogram with defined individual processes, such as charging, charactergeneration, developing, exposure, recharging and the like, and thetransfer of the print image in the form of a toner image to a movableprint carrier, which can also be a substrate which is moved on a furthertransport device occurs in the finish position. The transport devicewith the electrophotographic units is used only for receiving the tonerimage and for transporting the same into the transfer zone.

A known printing device requires considerable expenses in transportdevices. Furthermore, the printing device cannot be adjusted todifferent printing processes, nor easily provided with further units,also in a different sequence, between the start and finish positions.

Further printing devices are known, which are designed for definiteprinting processes, or wherein the electrophotographic units themselvescan be interconnected, as shown in U.S. Pat. No. 5,208,612. Thestructure of the printing device can also be provided without aconnection to the transport device with lined-up units, as disclosed inU.S. Pat. No. 4,569,582 and Patent Abstracts of Japan, vol. 2000, no.06, Sep. 22, 2002 and Japanese Patent Reference JP 200 08 1827 A (CanonInc.) dated Mar. 21, 2002. A flexible and universal adaptation of theprinting device to various printing processes is not possible there.

SUMMARY OF THE INVENTION

It is one object of this invention to provide a modularly constructedelectrophotographic printing device, which can be simply adapted tovarious printing processes.

In accordance with this invention, the support device has severalreceivers, located one behind the other in the transporting direction ofthe transporting device, with uniform mechanical and electricalinterfaces for attaching electrophotographic units, wherein these unitshave fastening elements equipped for the mechanical connection and, thesame as the receivers, have a bus system for the electrical connection.If a sufficient number of receivers is provided, a different number ofvarious units can also be required in different sequences for theprinting process. The units can be placed into any receiver andmechanically and electrically connected with the receiver, and thus canbe electrically connected with the central control unit. In this casethe bus system provides for different connections to the control unit,depending on the unit employed. Great flexibility and variation optionsfor different printing processes are provided by this design of theprinting device, which is solely provided by the number of units, theoccupied receivers and the sequence of the units between the start andfinish positions.

In one embodiment of this invention, the support device is assembledfrom at least two partial frames placed one behind the other, and thepartial frames are structurally identical and each has at least onereceiving position for an electrophotographic unit. Thus, it is possibleto construct the support device so that it is adapted to individualrequirements in the desired way. The number of electrophotographic unitsto be employed will mainly determine the number of partial frames.

It is also possible to provide the transporting device as a uniformcomponent conducted over all partial frames, or so that each partialframe has its own partial transporting device. The individual partialtransporting devices can be coupled with each other mechanically and/orby an electrical drive control for forming a uniform transportingdevice. The connection of the partial transporting devices assuressynchronous feeding, so that the substrate can be transported at asteady speed.

To assure an orderly supply of substrates, a centering module can beinstalled on the support device in the area of the start position. Thus,the centering module also represents a uniform component which can beconnected with the printing device as a kit.

A pre-centering module can be connected upstream of the centering modulein the transporting direction, and the pre-centering module can beinstalled on the support device or the centering module. Together withthe centering module, the pre-centering module assures an exactalignment of the substrate and its orderly feeding.

In one embodiment of this invention, a fixation module is arranged onthe support device or on the electrophotographic unit, which is used forpre-fixation or fixation of the toner applied to the substrate. Afterthe toner has been applied by one or more of the electrophotographicunits, the toner can be bonded to the surface of the substrate by thefixation module with a suitable energy application. Pre-fixation of thetoner following the completed toner application is practical in caseceramic colors, for example, are to be printed. Usually these ceramiccolors are applied to substrates made of glass or of a glass-ceramicmaterial. After leaving the printing device, the substrate with thepre-fixated toner is taken to a unit for final fixation, in which thetoner is fixated at a high temperature, and with ceramic toners isburned in, or in case of pressure-setting plastic material is cured.

The fixation module can have fastening elements, by which it can beconnected to the interfaces of the support device. Therefore theinterfaces are not only used for fastening and the exact alignment ofthe electrophotographic units, but also the fixation module or modules.

As mentioned above, a single fixation module can be provided for aprinting device. This would usually be arranged downstream in thetransport direction following the individual electrophotographic units.However, it is also possible for a fixation module to be assigned toeach one of the electrophotographic units, so that intermediatefixations become possible. This can be important in particular in caseswhere toners are intended to be printed on top of each other, forexample.

A delivery module can be provided in the area of the finish position. Itis possible with the latter to achieve orderly removal of the imprintedsubstrates. The delivery module can be a stacking device, for example,installed on the support device.

So that it is possible to dependably imprint flat substrates of largewall thickness in particular, for example glass plates, plates ofglass-ceramic material, wood panels or plastic panels, in one embodimentof this invention, every electrophotographic unit has a transfer systemfor transferring the toner to the substrate, and a primary charger isconnected upstream in the transport direction to the transfer system,and a secondary charger downstream in the transport direction. Thesurface of the substrate can be electrostatically charged by the primaryand secondary chargers. Charging brushes, charging rollers or chargingcoronas are conceivable chargers which preferably act on the surface ofthe substrate to be imprinted. During its passage through theelectrophotographic unit, the substrate is first charged by the primarycharger. Thereafter the substrate reaches the area of the transfersystem, where a toner transfer occurs.

Then the substrate is pushed ahead to the secondary charger, where it isrecharged. Depending on the size of the substrate or its positioning onthe transporting device, the substrate is connected either with theprimary charger, as well as the secondary charger, or only with thesecondary charger. During the coating process the substrate is always incontact with at least one charger and is charged by it.

For example, four electrophotographic units can be installed on thesupport device for forming a full color printing system, in whichcolored toners, namely cyan-, magenta-, yellow- or black-colored toneris stored. The individual colors can be imprinted on top of each other,if required with intermediate fixation, or imprinted next to each otherand mixed with each other. In this color further colors can be createdin a known manner.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is explained in view of exemplary embodiments representedin the drawings, wherein:

FIG. 1 is a printing device with an electrophotographic unit in aschematic view; and

FIG. 2 is a full color printing system in a schematic view.

DESCRIPTION OF PREFERRED EMBODIMENTS

A printing device for imprinting plate-shaped materials is representedin FIG. 1. One-color printing can be performed with this printingdevice.

The printing device has a support device 15, to which a transport system16 is assigned. Various components are arranged along the transportsystem. A substrate 6 can be transported between a start and a finishposition by the transport system. The substrate 6 can be, for example, aglass plate, a plate of glass-ceramic material, a ceramic plate or aplastic panel. Flexible substrates, such as plastic foils, leather,textiles, etc. are printed, which during the printing process then arefixed in place on a rigid backing which is located on or in a part ofthe transporting device. A pre-centering module 10 is arranged in thearea of the start position. The substrate is thus roughly positioned.Subsequently, with the transporting device 16 the substrate is fed to acentering module 11, in which it is exactly aligned. After completion ofthe positional alignment of the substrate, the substrate is fed to anelectrophotographic unit 12 a.

The electrophotographic unit 12 a has a developer, a photo conductor anda transfer system 12.2. The electrophotographic unit 12 a also has anexposure arrangement, by which a latent charge image can be created onthe photo conductor in a known manner. Based on this charge image, atoner material, stored in a separate toner cartridge of the developer,is transferred to the photo conductor by the developer. Then the photoconductor transfers the toner to the substrate directly, or using thetransfer system 12.2. In order to assure a toner transfer of goodquality to the substrate, a primary charger or charge means 12.1 isinstalled upstream of the transfer system 12.2, and a secondary chargeror charge means 12.3 is installed downstream. The primary and secondarycharge means 12.1, 12.3 apply a charge to the surface of the substrateto be imprinted. This is maintained during the entire coating process bythe arrangement of a primary charge means 12.1 and a secondary chargemeans 12.3.

At the completion of the toner application to the substrate, thesubstrate passes through a fixation module 13. In the fixation module 13the toner is bonded with the substrate by temperature effects.Thereafter the substrate reaches a delivery module 14, in which it isremoved from the printing device, enters a stacking device, for examplea buffer, or reaches further processing stations via an appropriatelinkage.

The support device 15 is embodied so that it has uniform mechanicalinterfaces for the electrophotographic unit 12 a, as well as for thefixation module 13. Accordingly, the electrophotographic unit 12 a andthe fixation module 13 have fastening elements, which are embodied in amanner matching the mechanical and electrical interfaces of the supportdevice. A rapid and simple assignment of these components to the supportdevice 15 is thus possible.

A full color printing system is shown in FIG. 2. Similar to theembodiment in accordance with FIG. 1, a support device 15 with atransport system 16 is used. In the embodiment shown in FIG. 2, thesupport device 15 is assembled from two partial frames 15 a, 15 b placedone behind the other. Each partial frame 15 a, 15 b has its own partialtransporting device 16 a, 16 b. The support device 15 has fivemechanical and electrical interfaces 20 located one behind the other, towhich an electrophotographic unit 12 a, 12 b, 12 c, 12 d, or a fixationmodule 13, can be fastened by fastening elements 21. Because themechanical and electrical interfaces are uniform, theelectrophotographic units 12 a to 12 d can be arranged in any desiredsequence. A toner is stored in each of the electrophotographic units 12a to 12 d.

However, the toners are differently colored, for example amagenta-colored toner can be stored in the first electrophotographicunit 12 a, a yellow toner can be stored in the electrophotographic unit12 b, in the electrophotographic unit 12 c a cyan-colored toner can bestored, and in the electrophotographic unit 12 d black toner can bestored.

As shown in FIG. 2, similar to FIG. 1 a pre-centering module 10, acentering module 11, a fixation module 13 and a delivery module 14 aremounted on the support device 15. A transport system 16 is also used,which links the individual components of the printing device with eachother.

1. In a modularly constructed electrophotographic printing device havinga support device (15) which has a transporting device (16) on which asubstrate to be imprinted can be transported between a start positionand a finish position, wherein a plurality of electrophotographic units(12 a to 12 d) can be attached to the support device (15) between thestart position and the finish position, which are designed as a photoconductor, a developer unit, or an exposure unit, the improvementcomprising: the support device (15) having a plurality of receiverslocated one behind an other in a transport direction of the transportingdevice (16), each of the plurality of receivers including a uniformmechanical and electrical interface for attaching one of theelectrophotographic units (12 a to 12 d) to the support device (15),wherein the electrophotographic units (12 a to 12 d) have fasteningelements equipped for a mechanical connection and have a bus system forthe electrical connection.
 2. In the printing device in accordance withclaim 1, wherein the support device (15) is assembled from at least twopartial frames placed one behind the other, and the partial frames arestructurally identical and each has at least one receiving position forone of the electrophotographic units.
 3. In the printing device inaccordance with claim 2, wherein one of the transporting device (16) isconducted as a uniform component over all partial frames, and eachpartial frame has a partial transporting device, and the individualpartial transporting devices are coupled with each other at least one ofmechanically and by an electrical drive control for forming the uniformtransporting device (16).
 4. In the printing device in accordance withclaim 3, wherein a centering module (11) is installed on the supportdevice (15) near the start position.
 5. In the printing device inaccordance with claim 4, wherein a fixation module (13) is arrangedfollowing each of the electrophotographic units (12 a to d).
 6. In theprinting device in accordance with claim 2, wherein a pre-centeringmodule (10) is connected upstream of the centering module (11) in thetransporting direction, and the pre-centering module (10) is installedon one of the support device (15) and the centering module (11).
 7. Inthe printing device in accordance with claim 6, wherein a fixationmodule (13) is arranged on one of the support device (15) and one of theelectrophotographic units (12 a to d) which is used to one of pre-fixand fix the toner applied to the substrate.
 8. In the printing device inaccordance with claim 7, wherein the fixation module (13) has fasteningelements for connection to interfaces of the support device (15).
 9. Inthe printing device in accordance with claim 6, wherein a fixationmodule (13) is arranged following each of the electrophotographic units(12 a to d).
 10. In the printing device in accordance with claim 9,wherein a delivery module (14) is attached to the support device (15)near the finish position.
 11. In the printing device in accordance withclaim 10, wherein a delivery module (14) linkable with a furtherprocessing device is arranged near the finish position.
 12. In theprinting device in accordance with claim 11, wherein each of theelectrophotographic units has a transfer system (12.2) for transferringthe toner to the substrate, and a primary charger (12.1) is connectedupstream in the transport direction to the transfer system, and asecondary charger (12.3) is connected downstream in the transportdirection.
 13. In the printing device in accordance with claim 12,wherein four of the electrophotographic units (12 a to d) are installedon the support device (15), wherein colored toners, including cyan,magenta, yellow or black colored toner is stored in the individualelectrophotographic units.
 14. In the printing device in accordance withclaim 12, wherein the printing device imprints flat rigid substrates.15. In the printing device in accordance with claim 1, wherein one ofthe transporting device (16) is conducted as a uniform component overall partial frames, and each partial frame has a partial transportingdevice, and the individual partial transporting devices are coupled witheach other at least one of mechanically and by an electrical drivecontrol for forming the uniform transporting device (16).
 16. In theprinting device in accordance with claim 1, wherein a centering module(11) is installed on the support device (15) near the start position.17. In the printing device in accordance with claim 16, wherein apre-centering module (10) is connected upstream of the centering module(11) in the transporting direction, and the pre-centering module (10) isinstalled on one of the support device (15) and the centering module(11).
 18. In the printing device in accordance with claim 1, wherein afixation module (13) is arranged on one of the support device (15) andone of the electrophotographic units (12 a to d) which is used to one ofpre-fix and fix the toner applied to the substrate.
 19. In the printingdevice in accordance with claim 18, wherein the fixation module (13) hasfastening elements for connection to interfaces of the support device(15).
 20. In the printing device in accordance with claim 1, wherein adelivery module (14) is attached to the support device (15) near thefinish position.
 21. In the printing device in accordance with claim 1,wherein a delivery module (14) linkable with a further processing deviceis arranged near the finish position.
 22. In the printing device inaccordance with claim 1, wherein each of the electrophotographic unitshas a transfer system (12.2) for transferring the toner to thesubstrate, and a primary charger (12.1) is connected upstream in thetransport direction to the transfer system, and a secondary charger(12.3) is connected downstream in the transport direction.
 23. In theprinting device in accordance with claim 1, wherein four of theelectrophotographic units (12 a to d) are installed on the supportdevice (15), wherein colored toners, including cyan, magenta, yellow orblack colored toner is stored in the individual electrophotographicunits.
 24. In a modularly constructed electrophotographic printingdevice having a support device (15) which has a transporting device (16)on which a substrate to be imprinted can be transported between a startposition and a finish position, wherein a plurality ofelectrophotographic units (12 a to 12 d) can be attached to the supportdevice (15) between the start position and the finish position, whichare designed as a photo conductor, a developer unit, or an exposureunit, the improvement comprising: the support device (15) having aplurality of receivers located one behind an other in a transportdirection of the transporting device (16), each of the plurality ofreceivers including a uniform mechanical and electrical interface forattaching one of the electrophotographic units (12 a to 12 d) to thesupport device, wherein the electrophotographic units (12 a to 12 d)have fastening elements equipped for a mechanical connection and have abus system for the electrical connection; wherein the printing deviceimprints flat rigid substrates.